Method of bonding utilizing imide ester derivatives of ethene maleic anhydride copolymers

ABSTRACT

Imide - ester derivatives of ethene - maleic anhydride copolymers are prepared in a two step reaction. These derivatives are useful as adhesives and protective coatings.

This is a division of application Ser. No. 102,539, filed Dec. 29, 1970and now U.S. Pat. No. 3,810,276.

BACKGROUND OF THE INVENTION

This invention relates to imide-ester copolymer derivatives, theirpreparation and use. In particular, this invention relates toimide-ester copolymers of ethene-maleic anhydride copolymers, theirpreparation and use.

Polymers and copolymers have a variety of uses, including use asprotective coatings and as adhesives. Epoxy resins, for example, haveexcellent adhesion properties producing a strong bond but the layer ofepoxy resin is not clear and transparent which would be a usefulproperty, particularly if the surface or surfaces to which it isadhering is transparent.

Resins which are useful as protective coatings and adhesives,particularly those producing a transparent bond are most desirable andit is the purpose of this invention to provide such a material.

SUMMARY OF THE INVENTION

Broadly, our invention is directed to imide-ester derivatives ofethene-maleic anhydride copolymers, their preparation and use asprotective coatings and adhesives. In a two step reaction process, a 1:1ethene-maleic anhydride linear copolymer is reacted with an aliphaticalcohol and then further reacted, catalytically, with an amino compound.These imide-ester derivatives find utility as protective coatings andform a transparent bond when utilized as an adhesive.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Broadly, I have found that an imide-ester copolymer derivative preparedin a two step reaction process has particular utility as a protectivecoating and an adhesive.

The process for preparing these derivatives comprises:

A. REACTING TOGETHER UNDER REFLUXING CONDITIONS A 1:1 LINEAR COPOLYMEROF ETHENE AND MALEIC ANHYDRIDE HAVING A MOLECULAR WEIGHT BETWEEN ABOUT10,000 AND 25,000 DISSOLVED IN A HYDROCARBON SOLVENT AND AN ALCOHOLSELECTED FROM THE GROUP CONSISTING OF C₈₋₂₀ saturated aliphaticalcohols, C₈₋₂₀ unsaturated aliphatic alcohols and mixtures thereof,

B. ADDING TO THE REACTION MIXTURE OF STEP (A) AN AMINO COMPOUND SELECTEDFROM THE GROUP CONSISTING OF N-(C₈₋₂₀)alkyl-1,3-diaminopropane,N-(C₈₋₂₀)alkenyl-1,3-diaminopropane, C₈₋₂₀ alkylamine, C₈₋₂₀alkenylamine and mixtures thereof, and a catalyst comprising a strongorgano-inorganic acid,

C. REACTING UNDER REFLUXING CONDITIONS THE REACTION MIXTURE OF STEP (B),AND

D. RECOVERING FROM THE REACTION MIXTURE, AN IMIDE-ESTER DERIVATIVE OFTHE ETHENE-MALEIC ANHYDRIDE COPOLYMER.

In accordance with this invention the copolymer derivatives are preparedin a two step reaction wherein the active ingredients comprise anethene-maleic anhydride copolymer, an alcohol and an amino compound. Theuseful copolymers are linear copolymers of ethene and maleic anhydridehaving an average molecular weight between about 10,000 and 25,000,particularly an average molecular weight between about 15,000 and20,000. These copolymers have the following recurring copolymeric unitstructure: ##EQU1##

When referring herein to a mole of the copolymer, I mean a "mole" or theformula weight of this recurring copolymeric unit.

The alcohols which I find useful are the C₈₋₂₀ saturated aliphaticalcohols, the C₈₋₂₀ unsaturated aliphatic alcohols and mixtures thereof,particularly dodecanol, tetradecanol, hexadecanol and octadecanol, with1 -dodecanol being particularly preferred.

The useful amino compounds include both amines and diamines, althoughthe diamines disclosed herein are preferred. The useful amines includeC₈₋₂₀ alkyl primary amines, C₈₋₂₀ alkenyl primary amine and mixturesthereof. Examples of these include 1-aminooctane, 1-aminodecane,1-aminododecane, 1-aminotetradecane, 1-aminohexadecane 1-aminooctadecaneand 1-aminooctadecene. They are available as mixtures of two, three ormore of these primary amines and are marketed by Armour & Company underthe tradename "Armeen." The preferred amino compounds are the diaminesincluding N-(C₈₋₂₀)-alkyl-1,3-diaminopropane,N-(C₈₋₂₀)-alkenyl-1,3-diaminopropane and mixtures thereof. Examples ofthese useful diamines include the octyl, decyl, dodecyl, tetradecyl,hexadecyl, octadecyl and octadecenyl 1,3-diaminopropanes. These productsare available as mixtures of four or more of these diamines and sold byArmour & Company under the tradename "Duomeen." A particularly preferredcommercial product is Duomeen T which is a mixture of 2% of thetetradecyl, 24% of the hexadecyl, 28% of the octadecyl and 46% of theoctadecenyl, 1,3-diaminopropanes.

I find that the mole ratio of the reactants can vary between certainlimits while still yielding useful imide-ester derivatives of thecopolymer. The mole ratio of the copolymer, i.e., the recurringcopolymeric unit, to alcohol to amino compound should be between about1:11/2: 1/4 and 1:1/2:3/4 with a preferred mole ratio being about1:1:1/2.

In the second reaction step of the process wherein the amino compound isreacted, a catalyst is required to effect the reaction. Useful catalystsinclude the strong organo-inorganic acids such as p-toluenesulfonic acidand benzenesulfonic acid. 1-2 wt.% of catalyst, based on the reactants,will catalize the reactions.

The process is performed and the reaction mechanism is postulated to beas follows: The copolymer is dissolved in a suitable hydrocarbon solventsuch as xylene to which is then added the alcohol. This mixture isheated under refluxing conditions while removing water of formationwhich forms to complete the reaction, with the reaction taking place atthe anhydride functions of the copolymer. A hemi-ester results from thisinitial step i.e., esters and acids are formed at the anhydride sitesdepending on the ratio of reactants used. The next step involves theaddition of catalyst and the amino compound to the reaction mixture anda continuation of the heating under refluxing conditions with theremoval of water of formation as it forms. In this step the imidefunctions form at some of the acid and ester sites to produce acopolymer derivative having imide and ester functions at what wereformerly anhydride sites.

It should be understood that since mixtures of the alcohols and theamino compounds may be employed and a copolymer serves as the backbonefor the anhydride sites and the reactions will occur randomly on thecopolymer, the possible compounds and isomers thereof which are formedare quite numerous and oftentimes difficult, if not impossible, tocatalogue completely. However, typical reactions can be postulated andan average or typical compound can be described although this does notthereby preclude the formation of compounds other than, or isomers of,that described. Certainly, where mixtures of reactants are employed thepossibilities are limitless. Further, varying the mole ratio of thereactants can change the number and type of groups formed on thecopolymer backbone. However it is possible to describe an "average" or"typical" number of imide and ester functions which are found per fourrecurring copolymeric units of the product of my process. This is setforth in Table I below for the useful mole ratio range of reactants aswell as the preferred mole ratio.

    ______________________________________                                                        No. of Substituent Groups Per                                 Mole Ratio of Reactants                                                                       Four Recurring Copolymeric Units                              ______________________________________                                        Copoly-                                                                       mer    Alcohol  Amine   Imide     Ester                                       ______________________________________                                        1      11/2     1/4     1         6                                           1      1        1/2     2         4                                           1       1/2     3/4     3         2                                           ______________________________________                                    

These imide-ester derivatives of ethene-maleic anhydride copolymersexhibit properties which make them useful as adhesives and protectivecoatings. As an adhesive, these derivatives will tightly affix bothsimilar and dissimilar materials to each other. Both porous andnon-porous, metal and non-metal materials may be affixed together. Thetypes of materials which can be adhered together include cardboard,paper, wood, ceramics, plastics, glass and metals, for example, brass,copper, steel and aluminum. The transparent quality of these derivativesmakes them particularly attractive for bonding transparent materialssuch as glass to each other or to non-transparent materials.

As a coating, these materials form a thin, continuous transparent filmto protect the surfaces of the metals and non-metals listed above. Thesefilms may be formed by dipping the material to be coated in a solutionof the derivative with a volatile solvent, permitting the excess todrain off and allowing the solvent to evaporate.

The following exemplify my invention.

EXAMPLE I

An imide-ester derivative of an ethene-maleic anhydride linear copolymerwas prepared.

63 grams (about 0.5 moles) of an ethene-maleic anhydride copolymerhaving an average molecular weight of 15,000 to 20,000 and sold byMonsanto Co. under the tradename DX-840 was dissolved in 500 ml. ofxylene. 140 grams of dodecanol (about 0.75 moles) were added to thismixture and refluxed for four hours while water of formation wasremoved. Then 3 grams of p-toluenesulfonic acid and 35 grams (about0.125 moles) of Duomeen T were added. This is a tradename of a productof Armour & Co. and is a mixture of N-alkyl-1,3 diaminopropanes andN-alkenyl-1,3 diaminopropane. The alkyl and alkenyl groups arederivatives of tallow acids and consist mainly of C₁₆ and C₁₈ normalsaturated hydrocarbon chains and C₁₈ mono-unsaturated chains.

The entire reaction mixture was heated under refluxing conditionsovernight (15 hours). Water of formation was removed during refluxing.The product was precipitated with 1500 ml. of methanol, the liquid wasdecanted, and the polymer was recovered and dried under vacuum at 250°F.Infra-red analysis of the polymer product identified imide and estersubstituents on the copolymer.

EXAMPLE II

The adhesive properties of these derivatives were demonstrated.

A 25% benzene solution of the copolymer derivative of Example I wasprepared. A few drops of the solution were placed between a series ofmaterials and held together at ambient temeperature overnight. In allinstances the materials were overlapped and the contact area wasapproximately 1/2 × 1 inch.

The results are shown in Table II below.

                  TABLE II                                                        ______________________________________                                        MATERIALS     RESULTS                                                         ______________________________________                                        2 strips of cardboard                                                                       Stuck fast together                                             Glass strip and brass                                                                       Stuck tightly together, trans-                                   strip         parent joint                                                   2 aluminum strips                                                                           Stuck fast together but could                                                  be pried apart by hand                                         2 wooden strips                                                                             Stuck fast together but could                                                  be pried apart by hand                                         2 steel strips                                                                              Stuck fast together and could                                                  not be pried apart by hand                                     2 glass slides                                                                              Stuck fast together and could                                                  not be pried apart by hand.                                                   Perfectly clear and transparent                                               joint                                                          ______________________________________                                    

EXAMPLE III

These derivatives were evaluated as protective films.

Portions of brass, aluminum, steel and glass strips were dipped into a25% benzene solution of the copolymer derivative of Example I. Thestrips were removed from the solution, the excess permitted to drain offand the remaining film allowed to dry at room temperature. The stripswere then placed in beakers containing 8% hydrochloric acid. In a fewminutes the uncoated portions of the metal strips were corroded whileall coated portions were unchanged.

I claim:
 1. A method of adhering paper, cardboard, ceramic, glass,plastics and metals to themselves or each other which comprises applyingto adjacent surfaces of said materials an imide-ester derivative of anethene-maleic anhydride copolymer and maintaining said surfaces togetherwhereby an adherent bond forms, said imide-ester derivative prepared bya process which comprises:a. reacting together under refluxingconditions a 1:1 linear copolymer of ethene and maleic anhydride havingan average molecular weight between about 10,000 and 25,000 dissolved ina hydrocarbon solvent and an alcohol selected from the group consistingof C₈₋₂₀ saturated aliphatic alcohols, C₈₋₂₀ unsaturated aliphaticalcohols and mixtures thereof, b. adding to the reaction mixture of step(a) an amino compound selected from the group consisting of N-(C₈₋₂₀)alkyl-1,3-diaminopropane, N-(C₈₋₂₀) alkenyl-1,3-diaminopropane, C₈₋₂₀alkylamine, C₈₋₂₀ alkenylamine and mixtures thereof and a catalystcomprising a strong organoinorganic acid, c. reacting under refluxingconditions the mixture of step (b), d. removing water of formationformed in step (c) from the reaction mixture, and e. recovering from thereaction mixture, an imideester derivative of the ethene-maleicanhydride copolymer.
 2. A method according to claim 1 wherein the aminocompound of step (b) is selected from the group consisting of N-(C₈₋₂₀)alkyl-1-3-diaminopropane, N-(C₈₋₂₀) alkenyl-1,3-diaminopropane andmixtures thereof.
 3. A method according to claim 1 wherein the copolymerhas an average molecular weight of between about 15,000 and 20,000, thealcohol is 1-dodecanol, the amino compound is a mixture of N-(C₁₄₋₁₈)alkyl-1,3-diaminopropane and N-(C₁₈) alkenyl 1,3-diaminopropane, thesolvent is xylene and the catalyst in p-toluene sulfonic acid.
 4. Amethod according to claim 1 wherein the mole ratio of the recurringcopolymeric unit:alcohol:amino compound is between about 1:1 1/2:1/4 and1:1/2:3/4.
 5. A method according to claim 3 wherein the mole ratio ofthe recurring copolymeric unit:alcohol:amino compound is about 1:1:1/2.